Involvement of Na(+), K(+)-ATPase and endogenous digitalis-like compounds in depressive disorders

Lupeol mitigates spinal cord injury by modulating microglial M1/M2 polarization via Na+/K+-ATPase-mediated mitophagy

Spinal cord injury (SCI) often results in severe disability or even death, with inflammation playing a critical role in hindering recovery. Although Lupeol is known for its potent anti-inflammatory properties, its specific role in SCI-induced inflammation remains underexplored. In this study, an in vitro inflammation model was established using LPS-stimulated BV2 microglia. Lupeol treatment effectively counteracted LPS-induced reductions in Na+/K+-ATPase (NKA) activity, suppression of mitophagy, M1 polarization of microglia, release of inflammatory factors, and increased pyroptosis. Mechanistically, Lupeol alleviated microglial inflammation by enhancing mitophagy through the activation of NKA activity. Furthermore, Lupeol upregulated NKA activity and mitophagy by activating the AMPKα2-mTOR-TFEB pathway. In vivo, a mouse model of SCI was established, and Lupeol was administered daily via intraperitoneal injection. Lupeol treatment significantly reduced neuronal loss, promoted microglial polarization from the M1 to the M2 phenotype, attenuated inflammation, and improved motor function recovery in SCI mice. In conclusion, Lupeol promotes mitophagy by enhancing NKA activity via the AMPK-mTOR-TFEB pathway, thereby suppressing the pro-inflammatory phenotype of microglia and mitigating SCI progression.

The brain-heart axis: integrative cooperation of neural, mechanical and biochemical pathways

The neural and cardiovascular systems are pivotal in regulating human physiological, cognitive and emotional states, constantly interacting through anatomical and functional connections referred to as the brain-heart axis. When this axis is dysfunctional, neurological conditions can lead to cardiovascular disorders and, conversely, cardiovascular dysfunction can substantially affect brain health. However, the mechanisms and fundamental physiological components of the brain-heart axis remain largely unknown. In this Review, we elucidate these components and identify three primary pathways: neural, mechanical and biochemical. The neural pathway involves the interaction between the autonomic nervous system and the central autonomic network in the brain. The mechanical pathway involves mechanoreceptors, particularly those expressing mechanosensitive Piezo protein channels, which relay crucial information about blood pressure through peripheral and cerebrovascular connections. The biochemical pathway comprises many endogenous compounds that are important mediators of neural and cardiovascular function. This multisystem perspective calls for the development of integrative approaches, leading to new clinical specialties in neurocardiology.

Onset of bipolar disorder by COVID-19: The roles of endogenous ouabain and the Na,K-ATPase

Bipolar Disorder (BD) is a psychiatric disorder marked by mood swings between manic and depressive episodes. The reduction in the Na,K-ATPase (NKA) enzyme activity and the inability of individuals with BD to produce endogenous ouabain (EO) at sufficient levels to stimulate this enzyme during stressful events are factors proposed for BD etiology. According to these hypotheses, reduction in NKA activity would result in altered neuronal resting potential, leading to BD symptoms. Recently, damage to the adrenals (EO synthesis site) in coronavirus disease (COVID-19) patients has been reported, however studies pointing to the pathophysiological mechanisms shared by these two diseases are scarce. Through a literature review, this study aims to correlate COVID-19 and BD, focusing on the role of NKA and EO to identify possible mechanisms for the worsening of BD due to COVID-19. The search in the PubMed database for the descriptors ("bipolar disorder" AND "Na,K-ATPase"), ("bipolar disorder" AND "endogenous ouabain"), ("covid-19" AND "bipolar disorder") and ("covid-19" AND "adrenal gland") resulted in 390 articles. The studies identified the adrenals as a vulnerable organ to SARS-CoV-2 infection. Cases of adrenal damage in patients with COVID-19 showing lower levels of adrenal hormones were reported. Cases of COVID-19 patients with symptoms of mania were reported worldwide. Given these results, we propose that adrenal cortical cell damage could lead to EO deficiency following neuronal NKA activity impairment, with small reductions in activity leading to mania and greater reductions leading to depression.

Differentially Altered Metabolic Pathways in the Amygdala of Subjects with Schizophrenia, Bipolar Disorder and Major Depressive Disorder

Background and hypothesis

A growing number of studies implicate a key role for metabolic processes in psychiatric disorders. Recent studies suggest that ketogenic diet may be therapeutically effective for subgroups of people with schizophrenia (SCZ), bipolar disorder (BPD) and possibly major depressive disorder (MDD). Despite this promise, there is currently limited information regarding brain energy metabolism pathways across these disorders, limiting our understanding of how brain metabolic pathways are altered and who may benefit from ketogenic diets. We conducted gene expression profiling on the amygdala, a key region involved in in the regulation of mood and appetitive behaviors, to test the hypothesis that amygdala metabolic pathways are differentially altered between these disorders.

Study Design

We used a cohort of subjects diagnosed with SCZ, BPD or MDD, and non-psychiatrically ill control subjects (n=15/group), together with our bioinformatic 3-pod analysis consisting of full transcriptome pathway analysis, targeted pathway analysis, leading-edge gene analysis and iLINCS perturbagen analysis.

Study Results

We identified differential expression of metabolic pathways in each disorder. Subjects with SCZ displayed downregulation of mitochondrial respiration and nucleotide metabolism pathways. In comparison, we observed upregulation of mitochondrial respiration pathways in subjects with MDD, while subjects with BPD displayed enrichment of pathways involved in carbohydrate metabolism. Several pathways associated with brain metabolism including immune system processes and calcium ion transport were also differentially altered between diagnosis groups.

Conclusion

Our findings suggest metabolic pathways are differentially altered in the amygdala in these disorders, which may impact approaches for therapeutic strategies.

Involvement of the Na+, K+-ATPase α1 Isoform and Endogenous Cardiac Steroids in Depression- and Manic-like Behaviors

Bipolar disorder (BD) is a severe and common chronic mental illness characterized by recurrent mood swings between depression and mania. The biological basis of the disease is poorly understood, and its treatment is unsatisfactory. Na+, K+-ATPase is a major plasma membrane transporter and signal transducer. The catalytic α subunit of this enzyme is the binding site for cardiac steroids. Three α isoforms of the Na+, K+-ATPase are present in the brain. Previous studies have supported the involvement of the Na+, K+-ATPase and endogenous cardiac steroids (ECS) in the etiology of BD. Decreased brain ECS has been found to elicit anti-manic and anti-depressive-like behaviors in mice and rats. However, the identity of the specific α isoform involved in these behavioral effects is unknown. Here, we demonstrated that decreasing ECS through intracerebroventricular (i.c.v.) administration of anti-ouabain antibodies (anti-Ou-Ab) decreased the activity of α1+/- mice in forced swimming tests but did not change the activity in wild type (wt) mice. This treatment also affected exploratory and anxiety behaviors in α1+/- but not wt mice, as measured in open field tests. The i.c.v. administration of anti-Ou-Ab decreased brain ECS and increased brain Na+, K+-ATPase activity in wt and α1+/- mice. The serum ECS was lower in α1+/- than wt mice. In addition, a study in human participants demonstrated that serum ECS significantly decreased after treatment. These results suggest that the Na+, K+-ATPase α1 isoform is involved in depressive- and manic-like behaviors and support that the Na+, K+-ATPase/ECS system participates in the etiology of BD.

Ouabain Reverts CUS-Induced Disruption of the HPA Axis and Avoids Long-Term Spatial Memory Deficits

Ouabain (OUA) is a cardiotonic steroid that modulates Na+, K+ -ATPase activity. OUA has been identified as an endogenous substance that is present in human plasma, and it has been shown to be associated with the response to acute stress in both animals and humans. Chronic stress is a major aggravating factor in psychiatric disorders, including depression and anxiety. The present work investigates the effects of the intermittent administration of OUA (1.8 μg/kg) during the chronic unpredictable stress (CUS) protocol in a rat's central nervous system (CNS). The results suggest that the intermittent OUA treatment reversed CUS-induced HPA axis hyperactivity through a reduction in (i) glucocorticoids levels, (ii) CRH-CRHR1 expression, and by decreasing neuroinflammation with a reduction in iNOS activity, without interfering with the expression of antioxidant enzymes. These changes in both the hypothalamus and hippocampus may reflect in the rapid extinction of aversive memory. The present data demonstrate the ability of OUA to modulate the HPA axis, as well as to revert CUS-induced long-term spatial memory deficits.

Vanadium in Bipolar Disorders-Reviving an Old Hypothesis

Bipolar disorder (BD) is a severe and common chronic mental illness. The biological basis of the disease is poorly understood and its treatment is unsatisfactory. Our previous studies supported the notion that alterations in Na⁺, K⁺-ATPase activity were involved in the etiology of BD. As various chemical elements inhibit Na⁺, K⁺-ATPase, we determined the concentration of 26 elements in the serum of BD patients before and after treatment and in postmortem brain samples from BD patients, and compared them with matched controls. The only element that was reduced significantly in the serum following treatment was vanadium (V). Furthermore, the concentration of V was significantly lower in the pre-frontal cortex of BD patients compared with that of the controls. Intracerebroventricular administration of V in mice elicited anxiolytic and depressive activities, concomitantly inhibited brain Na⁺, K⁺-ATPase activity, and increased extracellular signal-regulated kinase phosphorylation. A hypothesis associating V with BD was set forth decades ago but eventually faded out. Our results are in accord with the hypothesis and advocate for a thorough examination of the possible involvement of chemical elements, V in particular, in BD.

Potential of Heterogeneous Compounds as Antidepressants: A Narrative Review

Depression is a globally widespread disorder caused by a complicated interplay of social, psychological, and biological factors. Approximately 280 million people are suffering from depression worldwide. Traditional frontline antidepressants targeting monoamine neurotransmitters show unsatisfactory effects. The development and application of novel antidepressants for dissimilar targets are on the agenda. This review characterizes the antidepressant effects of multiple endogenous compounds and/or their targets to provide new insight into the working mechanism of antidepressants. We also discuss perspectives and challenges for the generation of novel antidepressants.

Pumpkin seed oil and zinc attenuate chronic mild stress perturbations in the cerebral cortex of rats

Purpose

This study aims to investigate the potential of pumpkin seed oil (PSO) and zinc to attenuate oxidative stress and neuroinflammation caused by chronic mild stress (CMS) in the cerebral cortex of male rats.

Design/methodology/approach

The rats were submitted to stress for six weeks and then the behavior of the rats was tested by forced swimming test (FST) and novel cage test. The treated groups were given venlafaxine (20 mg/kg), pumpkin seed oil (40 mg/kg) and zinc (4 mg/kg). The cortex homogenate was used for the detection of the oxidative stress parameters, the concentration of neurotransmitters, tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β), Na+/K+-ATPase activity, and the expression of histamine N-methyltransferase (Hnmt) and tyrosine hydroxylase (Th).

Findings

CMS causes a significant increase in immobility time in the FST and a significant decrease in the number of rearing in the novel cage test. CMS group showed a significant increase in alanine aminotransferase (ALT) activity, levels of cortisol, TNF-α, IL-1β, nitric oxide and malondialdehyde. CMS caused a significant decrease in the concentrations of serotonin, GABA, norepinephrine, and the activities of glutathione peroxidase, catalase, superoxide dismutase and Na+/K+-ATPase. CMS caused a marked reduction in the expression of Hnmt and Th in the cortex. PSO and zinc attenuated the Na+/K+-ATPase activity, oxidative parameters and neuroinflammation induced by the CMS, and this was reflected by the elevation of the concentration of neurotransmitters and reduction of cortisol and ALT, in addition to the behavior normalization. PSO and zinc attenuated the CMS by improving the antioxidant milieu and anti-inflammatory status of the cerebral cortex.

Originality/value

There are no studies on the effect of pumpkin seed oil on depression

LPS-induced impairment of Na+/K+-ATPase activity: ameliorative effect of tannic acid in mice

Acetylcholine is an excitatory neurotransmitter that modulates synaptic plasticity and communication, and it is essential for learning and memory processes. This neurotransmitter is hydrolyzed by acetylcholinesterase (AChE), which plays other cellular roles in processes such as inflammation and oxidative stress. Ion pumps, such as Na⁺/K⁺-ATPase and Ca²⁺-ATPase, are highly expressed channels that derive energy for their functions from ATP hydrolysis. Impairment of the cholinergic system and ion pumps is associated with neuropsychiatric diseases. Major depressive disorder (MDD) is an example of a complex disease with high morbidity and a heterogenous etiology. Polyphenols have been investigated for their therapeutic effects, and tannic acid (TA) has been reported to show neuroprotective and antidepressant-like activities. Animal models of depression-like behavior, such as lipopolysaccharide (LPS)-induced models of depression, are useful for investigating the pathophysiology of MDD. In this context, effects of TA were evaluated in an LPS-induced mouse model of depression-like behavior. Animals received TA for 7 days, and on the last day of treatment, LPS (830 μg/kg) was administered intraperitoneally. In vitro exposure of healthy brain to TA decreased the AChE activity. Additionally, this enzyme activity was decreased in cerebral cortex of LPS-treated mice. LPS injection increased the activity of Ca²⁺-ATPase in the cerebral cortex but decreased the enzyme activity in the hippocampus. LPS administration decreased Na⁺/K⁺-ATPase activity in the cerebral cortex, hippocampus, and striatum; however, TA administration prevented these changes. In conclusion, tannins may affect Na⁺/K⁺-ATPase and Ca²⁺-ATPase activities, which is interesting in the context of MDD.

Effect of Cardiotonic Steroid Marinobufagenin on Vascular Remodeling and Cognitive Impairment in Young Dahl-S Rats

The hypertensive response in Dahl salt-sensitive (DSS) rats on a high-salt (HS) diet is accompanied by central arterial stiffening (CAS), a risk factor for dementia, and heightened levels of a prohypertensive and profibrotic factor, the endogenous Na/K-ATPase inhibitor marinobufagenin (MBG). We studied the effect of the in vivo administration of MBG or HS diet on blood pressure (BP), CAS, and behavioral function in young DSS rats and normotensive Sprague-Dawley rats (SD), the genetic background for DSS rats. Eight-week-old male SD and DSS rats were given an HS diet (8% NaCl, n = 18/group) or a low-salt diet (LS; 0.1% NaCl, n = 14-18/group) for 8 weeks or MBG (50 µg/kg/day, n = 15-18/group) administered via osmotic minipumps for 4 weeks in the presence of the LS diet. The MBG-treated groups received the LS diet. The systolic BP (SBP); the aortic pulse wave velocity (aPWV), a marker of CAS; MBG levels; spatial memory, measured by a water maze task; and tissue collection for the histochemical analysis were assessed at the end of the experiment. DSS-LS rats had higher SBP, higher aPWV, and poorer spatial memory than SD-LS rats. The administration of stressors HS and MBG increased aPWV, SBP, and aortic wall collagen abundance in both strains vs. their LS controls. In SD rats, HS or MBG administration did not affect heart parameters, as assessed by ECHO vs. the SD-LS control. In DSS rats, impaired whole-heart structure and function were observed after HS diet administration in DSS-HS vs. DSS-LS rats. MBG treatment did not affect the ECHO parameters in DSS-MBG vs. DSS-LS rats. The HS diet led to an increase in endogenous plasma and urine MBG levels in both SD and DSS groups. Thus, the prohypertensive and profibrotic effect of HS diet might be partially attributed to an increase in MBG. The prohypertensive and profibrotic functions of MBG were pronounced in both DSS and SD rats, although quantitative PCR revealed that different profiles of profibrotic genes in DSS and SD rats was activated after MBG or HS administration. Spatial memory was not affected by HS diet or MBG treatment in either SD or DSS rats. Impaired cognitive function was associated with higher BP, CAS, and cardiovascular remodeling in young DSS-LS rats, as compared to young SD-LS rats. MBG and HS had similar effects on the cardiovascular system and its function in DSS and SD rats, although the rate of change in SD rats was lower than in DSS rats. The absence of a cumulative effect of increased aPWV and BP on spatial memory can be explained by the cerebrovascular and brain plasticity in young rats, which help the animals to tolerate CAS elevated by HS and MBG and to counterbalance the profibrotic effect of heightened MBG.

Imipramine induces hyperactivity in rats pretreated with ouabain: Implications to the mania switch induced by antidepressants

BACKGROUND

Bipolar disorder (BD) is a psychiatric disorder with complex therapy, besides the treatment with antidepressants induce a mania switch.

OBJECTIVE

Investigate the effect of the administration of imipramine (IMI) in rats submitted to intracerebroventricular (ICV) administrations of ouabain (OUA).

METHODS

Adult Wistar rats (n = 28) were submitted to only one ICV administration of OUA or artificial cerebrospinal fluid. On the 7th and 9th days following the ICV administration, animals were submitted to a behavioral analysis comprising open field task and forced swimming test. Between the 9th and 14th days, the rats received one daily intraperitoneal administration of IMI or saline (Sal). On the 15th day rats were submitted to the last session of behavioral analysis, followed by euthanasia. The frontal cortex and hippocampus were dissected for the subsequent biochemical assessments: oxidative parameters, and Na+/K+-ATPase activity.

RESULTS

OUA administration induced a manic-like effect on the 7th day and a depressive-like behavior on the 14th day. In contrast, IMI administration elicited significant mania switch-like effect on this same stage in animals who received OUA. OUA increased oxidative damage and activity of antioxidant enzymes in the brain of rats. IMI potentialized the oxidative damage of OUA. No significant differences between groups were observed in the Na+/K+-ATPase activity.

CONCLUSION

The present study suggests that residual effects from inhibition of the Na+K+ATPase could be involved in the manic-switch observed in bipolar patients. Besides, the OUA model of bipolar disorder could be used to study bipolar disorder in the context of mania switch.

Endogenous Cardiac Steroids in Bipolar Disorder: State of the Art

Bipolar disorder (BD) is a severe psychiatric illness with a poor prognosis and problematic, suboptimal, treatments. Treatments, borne of an understanding of the pathoetiologic mechanisms, need to be developed in order to improve outcomes. Dysregulation of cationic homeostasis is the most reproducible aspect of BD pathophysiology. Correction of ionic balance is the universal mechanism of action of all mood stabilizing medications. Endogenous sodium pump modulators (collectively known as endogenous cardiac steroids, ECS) are steroids which are synthesized in and released from the adrenal gland and brain. These compounds, by activating or inhibiting Na⁺, K⁺-ATPase activity and activating intracellular signaling cascades, have numerous effects on cell survival, vascular tone homeostasis, inflammation, and neuronal activity. For the past twenty years we have addressed the hypothesis that the Na⁺, K⁺-ATPase-ECS system may be involved in the etiology of BD. This is a focused review that presents a comprehensive model pertaining to the role of ECS in the etiology of BD. We propose that alterations in ECS metabolism in the brain cause numerous biochemical changes that underlie brain dysfunction and mood symptoms. This is based on both animal models and translational human results. There are data that demonstrate that excess ECS induce abnormal mood and activity in animals, while a specific removal of ECS with antibodies normalizes mood. There are also data indicating that circulating levels of ECS are lower in manic individuals, and that patients with BD are unable to upregulate synthesis of ECS under conditions that increase their elaboration in non-psychiatric controls. There is strong evidence for the involvement of ion dysregulation and ECS function in bipolar illness. Additional research is required to fully characterize these abnormalities and define future clinical directions.

Inhibition of endogenous ouabain by atrial natriuretic peptide is a guanylyl cyclase independent effect

Background

Endogenous ouabain (EO) and atrial natriuretic peptide (ANP) are important in regulation of sodium and fluid balance. There is indirect evidence that ANP may be involved in the regulation of endogenous cardenolides.

Methods

H295R are human adrenocortical cells known to release EO. Cells were treated with ANP at physiologic concentrations or vehicle (0.1% DMSO), with or without guanylyl cyclase inhibitor 1,2,4 oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Cyclic guanosine monophosphate (cGMP), the intracellular second messenger of ANP, was measured by a chemiluminescent immunoassay and EO was measured by radioimmunoassay of C18 extracted samples.

Results

EO secretion is inhibited by ANP treatment, with the most prolonged inhibition (90 min vs ≤ 60 min) occurring at physiologic ANP concentrations (50 pg/mL). Inhibition of guanylyl cyclase with ODQ, also reduces EO secretion. The inhibitory effects on EO release in response to cotreatment with ANP and ODQ appeared to be additive.

Conclusions

ANP inhibits basal EO secretion, and it is unlikely that this is mediated through ANP-A or ANP-B receptors (the most common natriuretic peptide receptors) or their cGMP second messenger; the underlying mechanisms involved are not revealed in the current studies. The role of ANP in the control of EO synthesis and secretion in vivo requires further investigation.

Ouabain inhibitor rostafuroxin attenuates dextromethorphan-induced manic potential

Dextromethorphan (DM) abuse produces mania-like symptoms in humans. ERK/Akt signaling activation involved in manic potential can be attenuated by the inhibition of ouabain-like cardiac steroids. In this study, increased phosphorylations of ERK/Akt and hyperlocomotion induced by DM (30 mg/kg, i.p./day × 7) were significantly protected by the ouabain inhibitor rostafuroxin (ROSTA), suggesting that DM induces the manic potential. ROSTA significantly attenuated DM-induced protein kinase C δ (PKCδ) phosphorylation, GluN2B (i.e., MDA receptor subunit) expression, and phospho-PKCδ/GluN2B interaction. DM instantly upregulated the nuclear factor erythroid-2-related factor 2 (Nrf2)-dependent system. However, DM reduced Nrf2 nuclear translocation, Nrf2 DNA binding activity, γ-glutamylcysteine mRNA expression, and subsequent GSH/GSSG level and enhanced oxidative parameters following 1-h of administration. ROSTA, PKCδ inhibitor rottlerin, and GluN2B inhibitor traxoprodil significantly attenuated DM-induced alterations in Nrf2-related redox parameters and locomotor activity induced by DM in wild-type mice. Importantly, in PKCδ knockout mice, DM failed to alter the above parameters. Further, ROSTA and traxoprodil also failed to enhance PKCδ depletion effect, suggesting that PKCδ is a critical target for the anti-manic potential of ROSTA or GluN2B antagonism. Our results suggest that ROSTA inhibits DM-induced manic potential by attenuating ERK/Akt activation, GluN2B/PKCδ signalings, and Nrf2-dependent system.

The role of sodium channels in direct current stimulation-axonal perspective

Transcranial neurostimulation methods are utilized as therapies for various neuropsychiatric disorders. Primarily, they entail the delivery of weak subthreshold currents across the brain, which modulate neuronal excitability. However, it is still a puzzle how such weak electrical fields actuate their effects. Previous studies showed that axons are the most sensitive subcellular compartment for direct current stimulation, and maximal polarization is achieved at their terminals. Nonetheless, polarization of axon terminals according to models was predicted to be weak, and the mechanism for substantial axon terminals polarization was obscure. Here, we show that a weak subthreshold electrical field modifies the conductance of voltage-dependent sodium channels in axon terminals, subsequently amplifying their membrane polarization. Moreover, we show that this amplification has substantial effects on synaptic functioning. Finally, we employ analytical modeling to explain how sodium currents modifications enhance axon terminal polarization. These findings relate to the mechanistic aspects of any neurostimulation technique.

Melatonin Successfully Rescues the Hippocampal Molecular Machinery and Enhances Anti-oxidative Activity Following Early-Life Sleep Deprivation Injury

Early-life sleep deprivation (ESD) is a serious condition with severe cognitive sequelae. Considering hippocampus plays an essential role in cognitive regulation, the present study aims to determine whether melatonin, a neuroendocrine beard with significant anti-oxidative activity, would greatly depress the hippocampal oxidative stress, improves the molecular machinery, and consequently exerts the neuro-protective effects following ESD. Male weanling Wistar rats (postnatal day 21) were subjected to ESD for three weeks. During this period, the animals were administered normal saline or melatonin (10 mg/kg) via intraperitoneal injection between 09:00 and 09:30 daily. After three cycles of ESD, the animals were kept under normal sleep/wake cycle until they reached adulthood and were sacrificed. The results indicated that ESD causes long-term effects, such as impairment of ionic distribution, interruption of the expressions of neurotransmitters and receptors, decreases in the levels of several antioxidant enzymes, and impairment of several signaling pathways, which contribute to neuronal death in hippocampal regions. Melatonin administration during ESD prevented these effects. Quantitative evaluation of cells also revealed a higher number of neurons in the melatonin-treated animals when compared with the saline-treated animals. As the hippocampus is critical to cognitive activity, preserving or even improving the hippocampal molecular machinery by melatonin during ESD not only helps us to better understand the underlying mechanisms of ESD-induced neuronal dysfunction, but also the therapeutic use of melatonin to counteract ESD-induced neuronal deficiency.

Ouabain induces memory impairment and alter the BDNF signaling pathway in an animal model of bipolar disorder: Cognitive and neurochemical alterations in BD model

BACKGROUND

The present study aims to evaluate the effects of ouabain on memory and neurotrophic parameters in the brains of rats.

METHODS

Wistar rats received an intracerebroventricular (ICV) injection of ouabain or artificial cerebrospinal fluid (aCSF). Seven and 14 days after ICV administration, the animals were subjected to the open-field and splash tests. Furthermore, the pro-BDNF, BDNF, TrkB, and CREB were assessed in the frontal cortex and hippocampus of the rats, in both seven and 14 days after ICV injection. The memory of the animals was tested by novel object recognition test (NOR) and inhibitory avoidance task (IA), only 14 days after ICV administration.

RESULTS

Ouabain increased locomotion and exploration in the animals seven days after its administration; however, 14 days after ICV, these behavioral parameters return to the basal level. Seven days after ouabain administration increased grooming behavior in the splash test; on the other hand, seven days after ouabain injection decreased the grooming behavior, which is considered an anhedonic response. Besides, ouabain decreased recognition index in the NOR and decreased aversive memory in the IA, when compared to the control group. The levels of pro-BDNF and BDNF decreased in the frontal cortex seven days after ouabain; but its receptor (TrkB) and CREB decreased seven and 14 days after ouabain, in both cerebral structures evaluated.

CONCLUSION

Ouabain-induced animal model of BD is an excellent model to assess memory alteration, observed in bipolar patients. Besides, the memory impairment induced by ouabain seems to be related to BDNF signaling pathway alterations.

Role of endogenous ouabain in the etiology of bipolar disorder

Background

Bipolar disorder is a severe psychiatric illness with poor prognosis and problematic and suboptimal treatments. Understanding the pathoetiologic mechanisms may improve treatment and outcomes.

Discussion

Dysregulation of cationic homeostasis is the most reproducible aspect of bipolar pathophysiology. Correction of ionic balance is the universal mechanism of action of all mood stabilizing medications. Recent discoveries of the role of endogenous sodium pump modulators (which include ‘endogenous ouabain’) in regulation of sodium and potassium distribution, inflammation, and activation of key cellular second messenger systems that are important in cell survival, and the demonstration that these stress-responsive chemicals may be dysregulated in bipolar patients, suggest that these compounds may be candidates for the coupling of environmental stressors and illness onset. Specifically, individuals with bipolar disorder appear to be unable to upregulate endogenous ouabain under conditions that require it, and therefore may experience a relative deficiency of this important regulatory hormone. In the absence of elevated endogenous ouabain, neurons are unable to maintain their normal resting potential, become relatively depolarized, and are then susceptible to inappropriate activation. Furthermore, sodium pump activity appears to be necessary to prevent inflammatory signals within the central nervous system. Nearly all available data currently support this model, but additional studies are required to solidify the role of this system.

Conclusion

Endogenous ouabain dysregulation appears to be a reasonable candidate for understanding the pathophysiology of bipolar disorder.

Proteomic Characterization of Synaptosomes from Human Substantia Nigra Indicates Altered Mitochondrial Translation in Parkinson's Disease

The pathological hallmark of Parkinson's disease (PD) is the loss of neuromelanin-containing dopaminergic neurons within the substantia nigra pars compacta (SNpc). Additionally, numerous studies indicate an altered synaptic function during disease progression. To gain new insights into the molecular processes underlying the alteration of synaptic function in PD, a proteomic study was performed. Therefore, synaptosomes were isolated by density gradient centrifugation from SNpc tissue of individuals at advanced PD stages (N = 5) as well as control subjects free of pathology (N = 5) followed by mass spectrometry-based analysis. In total, 362 proteins were identified and assigned to the synaptosomal core proteome. This core proteome comprised all proteins expressed within the synapses without regard to data analysis software, gender, age, or disease. The differential analysis between control subjects and PD cases revealed that CD9 antigen was overrepresented and fourteen proteins, among them Thymidine kinase 2 (TK2), mitochondrial, 39S ribosomal protein L37, neurolysin, and Methionine-tRNA ligase (MARS2) were underrepresented in PD suggesting an alteration in mitochondrial translation within synaptosomes.

Na+, K+-ATPase α Isoforms and Endogenous Cardiac Steroids in Prefrontal Cortex of Bipolar Patients and Controls

Bipolar disorder is a chronic multifactorial psychiatric illness that affects the mood, cognition, and functioning of about 1–2% of the world’s population. Its biological basis is unknown, and its treatment is unsatisfactory. The α1, α2, and α3 isoforms of the Na⁺, K⁺-ATPase, an essential membrane transporter, are vital for neuronal and glial function. The enzyme and its regulators, endogenous cardiac steroids like ouabain and marinobufagenin, are implicated in neuropsychiatric disorders, bipolar disorder in particular. Here, we address the hypothesis that the α isoforms of the Na⁺, K⁺-ATPase and its regulators are altered in the prefrontal cortex of bipolar disease patients. The α isoforms were determined by Western blot and ouabain and marinobufagenin by specific and sensitive immunoassays. We found that the α2 and α3 isoforms were significantly higher and marinobufagenin levels were significantly lower in the prefrontal cortex of the bipolar disease patients compared with those in the control. A positive correlation was found between the levels of the three α isoforms in all samples and between the α1 isoform and ouabain levels in the controls. These results are in accordance with the notion that the Na⁺, K⁺-ATPase-endogenous cardiac steroids system is involved in bipolar disease and suggest that it may be used as a target for drug development.

Pharmacological modulation of Na+, K+-ATPase as a potential target for OXA-induced neurotoxicity: Correlation between anxiety and cognitive decline and beneficial effects of 7-chloro-4-(phenylselanyl) quinoline

Growing evidence demonstrates that Oxaliplatin (OXA) is commonly associated with neurotoxicity that leads to emotional and cognitive impairments. The aim of the present study was to evaluate the OXA and Na⁺, K⁺-ATPase interaction and to correlate anxious behavior and cognitive impairment induced by this chemotherapeutic in Swiss mice. Also, considering the pharmacological modulation of Na⁺, K⁺-ATPase as a potential target for OXA-induced neurotoxicity, the therapeutic potential of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) was evaluated. Mice received OXA (10 mg kg^-1) or vehicle by intraperitoneal route (days 0 and 2). Oral administration of 4-PSQ (1 mg kg^-1) or vehicle was performed from days 2-14. Behavioral tasks started from day 12 onwards. On day 15, the animals were sacrificed, and the tissues collected. The effects of OXA and 4-PSQ on activity and expression level of Na⁺, K⁺-ATPase in the hippocampus and cerebral cortex, and the plasmatic corticosterone levels were determined. The findings demonstrated a significant positive correlation between anxious behavior and cognitive impairment induced by OXA. OXA caused an increase on the plasmatic corticosterone levels and reduced activity and expression level of Na⁺, K⁺-ATPase. 4-PSQ reduced both anxious behavior and cognitive impairment induced by OXA. 4-PSQ effect seems to be due to the modulation of Na⁺, K⁺-ATPase and reduction of corticosterone levels. Our results helped to expand knowledge about the mechanisms involved in the physiopathology of the OXA-induced neurotoxicity and strongly indicated that 4-PSQ may be a good prototype for the treatment of anxious behavior and cognitive impairment induced by OXA exposure.

Contribution of serotonergic and nitrergic pathways, as well as monoamine oxidase-a and Na+, K+-ATPase enzymes in antidepressant-like action of ((4-tert-butylcyclohexylidene) methyl) (4-methoxystyryl) sulfide (BMMS)

The present study investigated a possible antidepressant-like effect of ((4-tert-butylcyclohexylidene)methyl) (4-methoxystyryl) sulfide (BMMS) by using the forced swimming test (FST) and the tail suspension test (TST) in Swiss mice. The contribution of serotoninergic, glutamatergic and nitrergic systems in the antidepressant-like activity of BMMS was evaluated. We also examined the involvement of monoamine oxidase (MAO)-A, MAO-B and Na⁺, K⁺-ATPase activities in prefrontal cortex of mice. BMMS, (0.1-10 mg/kg, intragastrically (i.g.)) and fluoxetine (32 mg/kg, i.g.) decreased the immobility time in the FST and TST. The anti-immobility effect of BMMS (10 mg/kg, i.g.) in the TST was prevented by the pretreatment of mice with WAY100635 (0.1 mg/kg, subcutaneously (s.c.), a 5-HT_1A receptor antagonist), ketanserin (5 mg/kg, intraperitoneal (i.p.), a 5-HT_2A/2C receptor antagonist), and partially blocked by ondansetron (1 mg/kg, i.p., a 5-HT₃ receptor antagonist). The anti-immobility effect of BMMS (10 mg / kg, i.g.) was not avoided by pretreatment with MK-801 (0.01 mg/kg, s.c. a non-competitive N-methyl D-Aspartate (NMDA) receptor) in the TST. Pretreatment with L-arginine (500 mg/kg, i.p., a nitric oxide precursor) reversed partially the reduction in the immobility time elicited by BMMS (10 mg/kg, i.g.) in TST. BMMS altered Na⁺,K⁺-ATPase and MAO-A activities in prefrontal cortex of mice, but was not able to change the MAO-B activity. In conclusion, BMMS exerted an antidepressant-like effect in mice and serotonergic and nitrergic systems are involved in the antidepressant-like action of compound. BMMS modulated MAO-A and Na⁺, K⁺- ATPase activities in prefrontal cortex of mice.

Review of animal models of bipolar disorder that alter ion regulation

BACKGROUND

Accurate modeling of psychiatric disorders in animals is essential for advancement in our understanding and treatment of the severe mental illnesses. Of the multiple models available for bipolar illness, the ones that disrupt ion flux are currently the only ones that meet the three criteria for validity: face validity, construct validity, and predictive validity.

METHODS

A directed review was performed to evaluate animal models for mania in which ion dysregulation was the key intervention.

RESULTS

Three models are identified. All focus on disruption of the sodium potassium pump. One is pharmacologic and requires surgical insertion of an intracerebroventricular (ICV) cannula and subsequent administration of ouabain. Two are genetic and are based on heterozygote knockout (KO) of the alpha2 or alpha3 subunits of the sodium pump. Alpha2 KOs are believed to have altered glial function, and they do not appear to have a full array of manic symptoms. Alpha3 KOs appear to be the best characterized animal model for bipolar disorder currently available.

CONCLUSION

Animal models that disrupt ion regulation are more inclined to model both mania and depression; and are thus the most promising models available. However, other models are important for demonstrating mechanisms in important pathophysiologic aspect of bipolar disorder.

The neuroprotective role of melatonin in a gestational hypermethioninemia model

Elevated levels of methionine in blood characterize the hypermethioninemia, which may have genetic or non-genetic origin, as for example from high protein diet. Born rats from hypermethioninemic mothers presented cerebral oxidative stress, inhibition of Na⁺,K⁺-ATPase, memory deficit and ultrastructure cerebral changes. Melatonin is a hormone involved in circadian rhythm and has antioxidant effects. The aim of this study was to verify the possible neuroprotective effects of melatonin administration in hypermethioninemic pregnant rats on damage to biomolecules (Na⁺,K⁺-ATPase, sulfhydryl content and DNA damage index) and behavior (open field, novel object recognition and water maze tasks), as well as its effect on cells morphology by electron microscopy in offspring. Wistar female rats received methionine (2.68 μmol/g body weight) and/or melatonin (10 mg/kg body weight) by subcutaneous injections during entire pregnancy. Control rats received saline. Biochemical analyzes were performed at 21 and 30 days of life of offspring and behavioral analyzes were performed only at 30 days of age in male pups. Results showed that gestational hypermethioninemia diminished Na⁺,K⁺-ATPase activity and sulfhydryl content and increased DNA damage at 21 and 30 days of life. Melatonin was able to totally prevent Na⁺,K⁺-ATPase activity alteration at 21 days and partially prevent its alteration at 30 days of rats life. Melatonin was unable in to prevent sulfhydryl and DNA damage at two ages. It also improved DNA damage, but not at level of saline animals (controls). Regarding to behavioral tests, data showed that pups exposed to gestational hypermethioninemia decreased reference memory in water maze, spent more time to the center of the open field and did not differentiate the objects in the recognition test. Melatonin was able to prevent the deficit in novel object recognition task. Electron microscopy revealed ultrastructure alterations in neurons of hypermethioninemic at both ages of offspring, whose were prevented by melatonin. These findings suggest that melatonin may be a good neuroprotective to minimize the harmful effects of gestational hypermethioninemia on offspring.

Na+, K+-ATPase α3 isoform in frontal cortex GABAergic neurons in psychiatric diseases

Na⁺, K⁺-ATPase is an essential membrane transporter. In the brain, the α3 isoform of Na⁺, K⁺-ATPase is vital for neuronal function. The enzyme and its regulators, endogenous cardiac steroids (ECS), were implicated in neuropsychiatric disorders. GABAergic neurotransmission was also studied extensively in diseases such as schizophrenia and bipolar disorder (BD). Post mortem brain samples from subjects with depression, schizophrenia or BD and non-psychiatric controls were provided by the Stanley Medical Research Institute. ECS levels were determined by ELISA. Expression levels of the three Na⁺, K⁺-ATPase-α isoforms, α1, α2 and α3, were determined by Western blot analysis. The α3 levels in GABAergic neurons in different regions of the brain were quantified by fluorescence immunohistochemistry. The results show that Na⁺, K⁺ -ATPase α3 isoform levels were lower in GABAergic neurons in the frontal cortex in BD and schizophrenia as compared with the controls (n = 15 subjects per group). A study on a 'mini-cohort' (n = 3 subjects per group) showed that the α3 isoform levels were also lower in GABAergic neurons in the hippocampus, but not amygdala, of bipolar and schizophrenic subjects. In the temporal cortex, higher Na⁺, K⁺ -ATPase α3 protein levels were found in the three psychiatric groups. No significant differences in ECS levels were found in this brain area. This is the first report on the distribution of α3 in specific neurons in the human brain in association with mental illness. These results strengthen the hypothesis for the involvement of Na⁺, K⁺ -ATPase in neuropsychiatric diseases.

Na+ , K+ -ATPase activity in children with autism spectrum disorder: Searching for the reason(s) of its decrease in blood cells

Na+ , K+ -ATPase (NKA) activity, which establishes the sodium and potassium gradient across the cell membrane and is instrumental in the propagation of the nerve impulses, is altered in a number of neurological and neuropsychiatric disorders, including autism spectrum disorders (ASD). In the present work, we examined a wide range of biochemical and cellular parameters in the attempt to understand the reason(s) for the severe decrease in NKA activity in erythrocytes of ASD children that we reported previously. NKA activity in leukocytes was found to be decreased independently from alteration in plasma membrane fluidity. The different subunits were evaluated for gene expression in leukocytes and for protein expression in erythrocytes: small differences in gene expression between ASD and typically developing children were not apparently paralleled by differences in protein expression. Moreover, no gross difference in erythrocyte plasma membrane oxidative modifications was detectable, although oxidative stress in blood samples from ASD children was confirmed by increased expression of NRF2 mRNA. Interestingly, gene expression of some NKA subunits correlated with clinical features. Excess inhibitory metals or ouabain-like activities, which might account for NKA activity decrease, were ruled out. Plasma membrane cholesterol, but not phosphatidylcholine and phosphatidlserine, was slighty decreased in erythrocytes from ASD children. Although no compelling results were obtained, our data suggest that alteration in the erytrocyte lipid moiety or subtle oxidative modifications in NKA structure are likely candidates for the observed decrease in NKA activity. These findings are discussed in the light of the relevance of NKA in ASD. Autism Res 2018, 11: 1388-1403. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: The activity of the cell membrane enzyme NKA, which is instrumental in the propagation of the nerve impulses, is severely decreased in erythrocytes from ASD children and in other brain disorders, yet no explanation has been provided for this observation. We strived to find a biological/biochemical cause of such alteration, but most queries went unsolved because of the complexity of NKA regulation. As NKA activity is altered in many brain disorders, we stress the relevance of studies aimed at understanding its regulation in ASD.

Na+, K+-ATPase inhibition induces neuronal cell death in rat hippocampal slice cultures: Association with GLAST and glial cell abnormalities

Na⁺, K⁺-ATPase is a highly expressed membrane protein. Dysfunction of Na⁺, K⁺-ATPase has been implicated in the pathophysiology of several neurodegenerative and psychiatric disorders, however, the underlying mechanism of neuronal cell death resulting from Na⁺, K⁺-ATPase dysfunction is poorly understood. Here, we investigated the mechanism of neurotoxicity due to Na⁺, K⁺-ATPase inhibition using rat organotypic hippocampal slice cultures. Treatment with ouabain, a Na⁺, K⁺-ATPase inhibitor, increased the ratio of propidium iodide-positive cells among NeuN-positive cells in the hippocampal CA1 region, which was prevented by MK-801 and d-AP5, specific blockers of the N-methyl-d-aspartate (NMDA) receptor. EGTA, a Ca²⁺-chelating agent, also protected neurons from ouabain-induced injury. We observed that astrocytes expressed the glutamate aspartate transporter (GLAST), and ouabain changed the immunoreactive area of GFAP-positive astrocytes as well as GLAST. We also observed that ouabain increased the number of Iba1-positive microglial cells in a time-dependent manner. Furthermore, lithium carbonate, a mood-stabilizing drug, protected hippocampal neurons and reduced disturbances of astrocytes and microglia after ouabain treatment. Notably, lithium carbonate improved ouabain-induced decreases in GLAST intensity in astrocytes. These results suggest that glial cell abnormalities resulting in excessive extracellular concentrations of glutamate contribute to neurotoxicity due to Na⁺, K⁺-ATPase dysfunction in the hippocampal CA1 region.

Na⁺, K⁺-ATPase Signaling and Bipolar Disorder

Bipolar disorder (BD) is a severe and common chronic mental illness characterized by recurrent mood swings between depression and mania. The biological basis of the disease is poorly understood and its treatment is unsatisfactory. Although in past decades the "monoamine hypothesis" has dominated our understanding of both the pathophysiology of depressive disorders and the action of pharmacological treatments, recent studies focus on the involvement of additional neurotransmitters/neuromodulators systems and cellular processes in BD. Here, evidence for the participation of Na⁺, K⁺-ATPase and its endogenous regulators, the endogenous cardiac steroids (ECS), in the etiology of BD is reviewed. Proof for the involvement of brain Na⁺, K⁺-ATPase and ECS in behavior is summarized and it is hypothesized that ECS-Na⁺, K⁺-ATPase-induced activation of intracellular signaling participates in the mechanisms underlying BD. We propose that the activation of ERK, AKT, and NFκB, resulting from ECS-Na⁺, K⁺-ATPase interaction, modifies neuronal activity and neurotransmission which, in turn, participate in the regulation of behavior and BD. These observations suggest Na⁺, K⁺-ATPase-mediated signaling is a potential target for drug development for the treatment of BD.

Augmentation of Ouabain-Induced Increase in Heart Muscle Contractility by Akt Inhibitor MK-2206

Cardiac steroids (CSs), such as ouabain and digoxin, increase the force of contraction of heart muscle and are used for the treatment of congestive heart failure (CHF). However, their small therapeutic window limits their use. It is well established that Na+, K+-ATPase inhibition mediates CS-induced increase in heart contractility. Recently, the involvement of intracellular signal transduction was implicated in this effect. The aim of the present study was to test the hypothesis that combined treatment with ouabain and Akt inhibitor (MK-2206) augments ouabain-induced inotropy in mammalian models. We demonstrate that the combined treatment led to an ouabain-induced increase in contractility at concentrations at which ouabain alone was ineffective. This was shown in 3 experimental systems: neonatal primary rat cardiomyocytes, a Langendorff preparation, and an in vivo myocardial infarction induced by left anterior descending coronary artery (LAD) ligation. Furthermore, cell viability experiments revealed that this treatment protected primary cardiomyocytes from MK-2206 toxicity and in vivo reduced the size of scar tissue 10 days post-LAD ligation. We propose that Akt activity imposes a constant inhibitory force on muscle contraction, which is attenuated by low concentrations of MK-2206, resulting in potentiation of the ouabain effect. This demonstration of the increase in the CS effect advocates the development of the combined treatment in CHF.

Endogenous Ouabain and Related Genes in the Translation from Hypertension to Renal Diseases

The endogenous ouabain (EO) is a steroid hormone secreted by the adrenal gland with cardio-tonic effects. In this article, we have reviewed and summarized the most recent reports about EO, particularly with regard to how it may interact with specific genetic backgrounds. We have focused our attention on the EO’s potential pathogenic role in several diseases, including renal failure, essential hypertension and heart failure. Notably, these reports have demonstrated that EO acts as a pro-hypertrophic and growth-promoting hormone, which might lead to a cardiac remodeling affecting cardiovascular functions and structures. In addition, a possible role of EO in the development of acute kidney injury has been hypothesized. During the last decays, many important improvements permitted a deeper understanding of EO’s metabolisms and functions, including the characteristics of its receptor and the effects of its activation. Such progresses indicated that EO has significant implications in the pathogenesis of many common diseases. The patho-physiological role of EO in the development of hypertension and other cardiac and renal complications have laid the basis for the development of a new selective compound that could selectively modulate the genetic and molecular mechanisms involved in EO’s action. It is evident that the knowledge of EO has incredibly increased; however, many important areas remain to be further investigated.

Reduction in endogenous cardiac steroids protects the brain from oxidative stress in a mouse model of mania induced by amphetamine

OBJECTIVES

Bipolar disorder (BD) is a severe mental illness characterized by episodes of mania and depression. Numerous studies have implicated the involvement of endogenous cardiac steroids (CS), and their receptor, Na⁺, K⁺ -ATPase, in BD. The aim of the present study was to examine the role of brain oxidative stress in the CS-induced behavioral effects in mice.

METHODS

Amphetamine (AMPH)-induced hyperactivity, assessed in the open-field test, served as a model for manic-like behavior in mice. A reduction in brain CS was obtained by specific and sensitive anti-ouabain antibodies. The level of oxidative stress was tested in the hippocampus and frontal cortex by measuring the activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as the levels of antioxidant non-protein thiols (NPSH) and oxidative damage biomarkers thiobarbituric acid reactive substances (TBARS) and protein carbonyl (PC).

RESULTS

AMPH administration resulted in a marked hyperactivity and increased oxidative stress, as manifested by increased SOD activity, decreased activities of CAT and GPx, reduced levels of NPSH and increased levels of TBARS and PC. The administration of anti-ouabain antibodies, which reduced the AMPH-induced hyperactivity, protected against the concomitant oxidative stress in the brain.

CONCLUSIONS

Our results demonstrate that oxidative stress participates in the effects of endogenous CS on manic-like behavior induced by AMPH. These finding support the notion that CS and oxidative stress may be associated with the pathophysiology of mania and BD.

Much More than a Cardiotonic Steroid: Modulation of Inflammation by Ouabain

Since the discovery of ouabain as a cardiotonic steroid hormone present in higher mammals, research about it has progressed rapidly and several of its physiological and pharmacological effects have been described. Ouabain can behave as a stress hormone and adrenal cortex is its main source. Direct effects of ouabain are originated due to the binding to its receptor, the Na⁺/K⁺-ATPase, on target cells. This interaction can promote Na⁺ transport blockade or even activation of signaling transduction pathways (e.g., EGFR/Src-Ras-ERK pathway activation), independent of ion transport. Besides the well-known effect of ouabain on the cardiovascular system and blood pressure control, compelling evidence indicates that ouabain regulates a number of immune functions. Inflammation is a tightly coordinated immunological function that is also affected by ouabain. Indeed, this hormone can modulate many inflammatory events such as cell migration, vascular permeability, and cytokine production. Moreover, ouabain also interferes on neuroinflammation. However, it is not clear how ouabain controls these events. In this brief review, we summarize the updates of ouabain effect on several aspects of peripheral and central inflammation, bringing new insights into ouabain functions on the immune system.

The Study of Postmortem Human Synaptosomes for Understanding Alzheimer's Disease and Other Neurological Disorders: A Review

Synaptic dysfunction is thought to play important roles in the pathophysiology of many neurological diseases, including Alzheimer’s disease, Parkinson’s disease, and schizophrenia. Over the past few decades, there have been systematic efforts to collect postmortem brain tissues via autopsies, leading to the establishment of dozens of human brain banks around the world. From cryopreserved human brain tissues, it is possible to isolate detached-and-resealed synaptic terminals termed synaptosomes, which remain metabolically and enzymatically active. Synaptosomes have become important model systems for studying human synaptic functions, being much more accessible than ex vivo brain slices or primary neuronal cultures. Here we review recent advances in the establishment of human brain banks, the isolation of synaptosomes, their biological activities, and various analytical techniques for investigating their biochemical and ultrastructural properties. There are unique insights to be gained by directly examining human synaptosomes, which cannot be substituted by animal models. We will also discuss how human synaptosome research has contributed to better understanding of neurological disorders, especially Alzheimer’s disease.

The sensitivity of Na+, K+ ATPase as an indicator of blood diseases

BACKGROUND

Blood-related hereditary diseases are widespread in Eastern and SouthWestern regions of Saudi Arabia until recently. In this study, we used Na⁺, K⁺ATPase as an enzymatic indicator for the diagnosis of the diseases.

MATERIALS AND METHODS

Individuals with different blood diseases (iron deficiency (n=13), anemia (n=14), thalassemia (n=16) and sickle cell anemia (n=12) were studied for Na⁺, K⁺-ATPase activity in the plasma membrane of red blood cell and compared with those of the healthy ones (n=20) of the same age and gender living in Jeddah, Saudi Arabia.

RESULTS

There was a significant elevation in the specific activity of Na⁺, K⁺ATPase in individuals with anemia compared with those of control (0.0094 + 0.001 nmol / mg protein/min versus 0.0061 ± 0.001). On the other hand, there was a significant reduction in enzyme activity in thalassemia (0.0028 ± 0.002 nmol / mg protein/min) and sickle cell anemia cases (0.0042 ±0.001 nmol / mg protein/min) compared to the control group. The cut off value for Na⁺, K⁺ATPase activity is 0.005 µmol Pi/min-showing 94% sensitivity and 93% specificity for the differentiation of blood abnormality.

CONCLUSION

It can be recommended that the activity of Na⁺, K⁺-ATPase can be used for the diagnosis of individuals with blood diseases/disorders.

Selective inhibition of MAO-A activity results in an antidepressant-like action of 2-benzoyl 4-iodoselenophene in mice

Depression is a leading cause of disability worldwide. For this reason, the aim of this study was to investigate the possible antidepressant-like activity of 2-benzoyl-4-iodoselenophene (C₁₇H₁₁IOSe), a selenophene compound, in two well-consolidated behavioral assays for screening antidepressant activity (forced swimming test and tail suspension test) in mice. In order to investigate the mechanism of action of C₁₇H₁₁IOSe, it was investigated the activities of cerebral enzymes: monoamine oxidase MAO A and B and Na⁺, K⁺ ATPase, and if an inhibitor of serotonin synthesis, p-chlorophenylalanine (pCPA) (100mg/kg) blocks the antidepressant-like effect of C₁₇H₁₁IOSe. Swiss mice received (C₁₇H₁₁IOSe) (5-50mg/kg) or canola oil by the intragastric (i.g.) route before behavioral tests. The results showed that C₁₇H₁₁IOSe at dose range of 5-50mg/kg decreased immobility time in the tail suspension test. In the forced swimming test, C₁₇H₁₁IOSe reduced the immobility time at the doses of 10 and 50mg/kg. C₁₇H₁₁IOSe differently affected the cerebral cortical Na⁺, K⁺ ATPase; the effects on this enzyme were dependent of the dose tested. At a dose of 10mg/kg, the compound increased Na⁺, K⁺ ATPase activity, while the activity was inhibited at a dose of 50mg/kg. pCPA blocked the antidepressant-like action of C₁₇H₁₁IOSe in mice. Therefore, C₁₇H₁₁IOSe (5-50mg/kg) selectively inhibited MAO-A activity in cerebral cortices of mice. The modulation of serotonergic system contributed to the antidepressant-like action of C₁₇H₁₁IOSe in mice.

Predicting the physiological response of Tivela stultorum hearts with digoxin from cardiac parameters using artificial neural networks

Multi-layer perceptron artificial neural networks (MLP-ANNs) were used to predict the concentration of digoxin needed to obtain a cardio-activity of specific biophysical parameters in Tivela stultorum hearts. The inputs of the neural networks were the minimum and maximum values of heart contraction force, the time of ventricular filling, the volume used for dilution, heart rate and weight, volume, length and width of the heart, while the output was the digoxin concentration in dilution necessary to obtain a desired physiological response. ANNs were trained, validated and tested with the dataset of the in vivo experiment results. To select the optimal network, predictions for all the dataset for each configuration of ANNs were made, a maximum 5% relative error for the digoxin concentration was set and the diagnostic accuracy of the predictions made was evaluated. The double-layer perceptron had a barely higher performance than the single-layer perceptron; therefore, both had a good predictive ability. The double-layer perceptron was able to obtain the most accurate predictions of digoxin concentration required in the hearts of T. stultorum using MLP-ANNs.

Correlative study of peripheral ATP1A1 gene expression level to anxiety severity score on major depressive disorder patients

BACKGROUND

Major depressive disorder (MDD) frequently co-occurs with other psychiatric problems. Our previous study showed that ATP1A1 gene expression level was significantly decreased in MDD patients. This research explores the potential correlations between the ATP1A1 expression level reduction and MDD patients' clinical manifestation.

METHODS

All participant patients were diagnosed by Diagnostic and Statistical Manual of Mental Disorders - 4th edition (DSM-IV). Hamilton rating scale for depression (HAM-D) and anxiety (HAM-A) were applied to group patients into different categories. ATP1A1 expression level was measured by reverse transcript real-time polymerase chain reaction.

RESULTS

ATP1A1 expression levels of all MDD subgroups showed significant reduction compared to the control group (p<0.01). Further, the trend of ATP1A1 expression level reduction is significantly related to MDD patients' HAM-A scores (p<0.01). However, there was no significance between ATP1A1 level and HAM-D scores (p>0.05).

CONCLUSIONS

ATP1A1 expression level reduction is related to MDD anxiety score, which may be an explanation for the clinical manifestations and the underlining physiological mechanisms.

Endogenous cardiac steroids in animal models of mania

OBJECTIVES

Bipolar disorder (BD) is a complex psychiatric disorder characterized by mania and depression. Alterations in brain Na(+) , K(+) -ATPase and cardiac steroids (CSs) have been detected in BD, raising the hypothesis of their involvement in this pathology. The present study investigated the behavioral and biochemical consequences of a reduction in endogenous brain CS activity in animal models of mania.

METHODS

Amphetamine (AMPH)-induced hyperactivity in BALB/c and black Swiss mice served as a model of mania. Behavior was evaluated in the open-field test in naïve mice or in mice treated with anti-ouabain antibodies. CS levels were determined by enzyme-linked immunosorbent assay (ELISA), using sensitive and specific anti-ouabain antibodies. Extracellular signal-regulated kinase (ERK) and protein kinase B (Akt) phosphorylation levels in the frontal cortex were determined by western blot analysis.

RESULTS

Administration of AMPH to BALB/c and black Swiss mice resulted in a marked increase in locomotor activity, accompanied by a threefold increase in brain CSs. The lowering of brain CSs by the administration of anti-ouabain antibodies prevented the hyperactivity and the increase in brain CS levels. AMPH caused an increase in phosphorylated ERK (p-ERK) and phosphorylated Akt (p-Akt) levels in the frontal cortex, which was significantly reduced by administration of the antibodies. A synthetic 'functional antagonist' of CSs, 4-(3'α-15'β-dihydroxy-5'β-estran-17'β-yl) furan-2-methyl alcohol, also resulted in attenuation of AMPH-induced hyperactivity.

CONCLUSIONS

These results are in accordance with the notion that malfunctioning of the Na(+) , K(+) -ATPase/CS system may be involved in the manifestation of mania and identify this system as a potential new target for drug development.

Specialized Functional Diversity and Interactions of the Na,K-ATPase

Na,K-ATPase is a protein ubiquitously expressed in the plasma membrane of all animal cells and vitally essential for their functions. A specialized functional diversity of the Na,K-ATPase isozymes is provided by molecular heterogeneity, distinct subcellular localizations, and functional interactions with molecular environment. Studies over the last decades clearly demonstrated complex and isoform-specific reciprocal functional interactions between the Na,K-ATPase and neighboring proteins and lipids. These interactions are enabled by a spatially restricted ion homeostasis, direct protein-protein/lipid interactions, and protein kinase signaling pathways. In addition to its "classical" function in ion translocation, the Na,K-ATPase is now considered as one of the most important signaling molecules in neuronal, epithelial, skeletal, cardiac and vascular tissues. Accordingly, the Na,K-ATPase forms specialized sub-cellular multimolecular microdomains which act as receptors to circulating endogenous cardiotonic steroids (CTS) triggering a number of signaling pathways. Changes in these endogenous cardiotonic steroid levels and initiated signaling responses have significant adaptive values for tissues and whole organisms under numerous physiological and pathophysiological conditions. This review discusses recent progress in the studies of functional interactions between the Na,K-ATPase and molecular microenvironment, the Na,K-ATPase-dependent signaling pathways and their significance for diversity of cell function.

Essential Opposite Roles of ERK and Akt Signaling in Cardiac Steroid-Induced Increase in Heart Contractility

Interaction of cardiac steroids (CS) with the Na(+), K(+)-ATPase elicits, in addition to inhibition of the enzyme's activity, the activation of intracellular signaling such as extracellular signal-regulated (ERK) and protein kinase B (Akt). We hypothesized that the activities of these pathways are involved in CS-induced increase in heart contractility. This hypothesis was tested using in vivo and ex vivo wild type (WT) and sarcoplasmic reticulum Ca(2+) atpase1a-deficient zebrafish (accordion, acc mutant) experimental model. Heart contractility was measured in vivo and in primary cardiomyocytes in WT zebrafish larvae and acc mutant. Ca(2+) transients were determined ex vivo in adult zebrafish hearts. CS dose dependently augmented the force of contraction of larvae heart muscle and cardiomyocytes and increased Ca(2+) transients in WT but not in acc mutant. CS in vivo increased the phosphorylation rate of ERK and Akt in the adult zebrafish heart of the two strains. Pretreatment of WT zebrafish larvae or cardiomyocytes with specific MAPK inhibitors completely abolished the CS-induced increase in contractility. On the contrary, pretreatment with Akt inhibitor significantly enhanced the CS-induced increase in heart contractility both in vivo and ex vivo without affecting CS-induced Ca(2+) transients. Furthermore, pretreatment of the acc mutant larvae or cardiomyocytes with Akt inhibitor restored the CS-induced increase in heart contractility also without affecting Ca(2+) transients. These results support the notion that the activity of MAPK pathway is obligatory for CS-induced increases in heart muscle contractility. Akt activity, on the other hand, plays a negative role, via Ca(2+) independent mechanisms, in CS action. These findings point to novel potential pharmacological intervention to increase CS efficacy.

Curcumin Mediated Attenuation of Carbofuran Induced Oxidative Stress in Rat Brain

The indiscriminate use of carbofuran to improve crop productivity causes adverse effects in nontargets including mammalian systems. The objective of this study was to evaluate carbofuran induced oxidative stress in rat brain stem and its attenuation by curcumin, a herbal product. Out of 6 groups of rats, 2 groups received two different doses of carbofuran, that is, 15 and 30% of LD₅₀, respectively, for 30 days. Out of these, 2 groups receiving same doses of carbofuran were pretreated with curcumin (100 mg/kg body weight). The levels of antioxidants, TBARS, GSH, SOD, catalase, and GST were determined in rat brain stem. The 2 remaining groups served as placebo and curcumin treated, respectively. The data suggested that carbofuran at different doses caused significant alterations in the levels of TBARS and GSH in dose dependent manner. The TBARS and GSH contents were elevated. The activities of SOD, catalase, and GST were significantly inhibited at both doses of carbofuran. The ratio of P/A was also found to be sharply increased. The pretreatment of curcumin exhibited significant protection from carbofuran induced toxicity. The results suggested that carbofuran at sublethal doses was able to induce oxidative stress in rat brain which could be attenuated by curcumin.

Roads Less Traveled: Sexual Dimorphism and Mast Cell Contributions to Migraine Pathology

Migraine is a common, little understood, and debilitating disease. It is much more prominent in women than in men (~2/3 are women) but the reasons for female preponderance are not clear. Migraineurs frequently experience severe comorbidities, such as allergies, depression, irritable bowel syndrome, and others; many of the comorbidities are more common in females. Current treatments for migraine are not gender specific, and rarely are migraine and its comorbidities considered and treated by the same specialist. Thus, migraine treatments represent a huge unmet medical need, which will only be addressed with greater understanding of its underlying pathophysiology. We discuss the current knowledge about sex differences in migraine and its comorbidities, and focus on the potential role of mast cells (MCs) in both. Sex-based differences in pain recognition and drug responses, fluid balance, and the blood–brain barrier are recognized but their impact on migraine is not well studied. Furthermore, MCs are well recognized for their prominent role in allergies but much less is known about their contributions to pain pathways in general and migraine specifically. MC-neuron bidirectional communication uniquely positions these cells as potential initiators and/or perpetuators of pain. MCs can secrete nociceptor sensitizing and activating agents, such as serotonin, prostaglandins, histamine, and proteolytic enzymes that can also activate the pain-mediating transient receptor potential vanilloid channels. MCs express receptors for both estrogen and progesterone that induce degranulation upon binding. Furthermore, environmental estrogens, such as Bisphenol A, activate MCs in preclinical models but their impact on pain pathways or migraine is understudied. We hope that this discussion will encourage scientists and physicians alike to bridge the knowledge gaps linking sex, MCs, and migraine to develop better, more comprehensive treatments for migraine patients.

Targeting astrocytes in bipolar disorder

Astrocytes are homeostatic cells of the central nervous system, which are critical for development and maintenance of synaptic transmission and hence of synaptically connected neuronal ensembles. Astrocytic densities are reduced in bipolar disorder, and therefore deficient astroglial function may contribute to overall disbalance in neurotransmission and to pathological evolution. Classical anti-bipolar drugs (lithium salts, valproic acid and carbamazepine) affect expression of astroglial genes and modify astroglial signalling and homeostatic cascades. Many effects of both antidepressant and anti-bipolar drugs are exerted through regulation of glutamate homeostasis and glutamatergic transmission, through K(+) buffering, through regulation of calcium-dependent phospholipase A2 (that controls metabolism of arachidonic acid) or through Ca(2+) homeostatic and signalling pathways. Sometimes anti-depressant and anti-bipolar drugs exert opposite effects, and some effects on gene expression in drug treated animals are opposite in neurones vs. astrocytes. Changes in the intracellular pH induced by anti-bipolar drugs affect uptake of myo-inositol and thereby signalling via inositoltrisphosphate (InsP3), this being in accord with one of the main theories of mechanism of action for these drugs.

Severe Headache or Migraine History is Inversely Correlated With Dietary Sodium Intake: NHANES 1999-2004

Objective

We investigated whether dietary sodium intake from respondents of a national cross‐sectional nutritional study differed by history of migraine or severe headaches.

Background

Several lines of evidence support a disruption of sodium homeostasis in migraine.

Design

Our analysis population was 8819 adults in the 1999–2004 National Health and Nutrition Examination Survey (NHANES) with reliable data on diet and headache history. We classified respondents who reported a history of migraine or severe headaches as having probable history of migraine. To reduce the diagnostic conflict from medication overuse headache, we excluded respondents who reported taking analgesic medications. Dietary sodium intake was measured using validated estimates of self‐reported total grams of daily sodium consumption and was analyzed as the residual value from the linear regression of total grams of sodium on total calories. Multivariable logistic regression that accounted for the stratified, multistage probability cluster sampling design of NHANES was used to analyze the relationship between migraine and dietary sodium.

Results

Odds of probable migraine history decreased with increasing dietary sodium intake (odds ratio = 0.93, 95% confidence interval = 0.87, 1.00, P = .0455). This relationship was maintained after adjusting for age, sex, and body mass index (BMI) with slightly reduced significance (P = .0505). In women, this inverse relationship was limited to those with lower BMI (P = .007), while in men the relationship did not differ by BMI. We likely excluded some migraineurs by omitting frequent analgesic users; however, a sensitivity analysis suggested little effect from this exclusion.

Conclusions

This study is the first evidence of an inverse relationship between migraine and dietary sodium intake. These results are consistent with altered sodium homeostasis in migraine and our hypothesis that dietary sodium may affect brain extracellular fluid sodium concentrations and neuronal excitability.